As is known in the art, bearingless motors levitate and drive a rotor with a single stator unit. This approach can eliminate mechanical bearings in a compact form factor.
As is also known, bearingless motor technology has drawn international research efforts, which has led to developments of bearingless motors of various types. Bearingless motors are found to be particularly useful in applications such as blood pumps and pumps for high-purity chemical processes. Bearingless slice motors, developed by Barletta et al. (1996) and further studied by Silber et al. (2005), are particularly suitable for such applications. Bearingless slice motors levitate a pump impeller passively in axial and tilting directions and actively in two radial directions. The passive levitation is realized with reluctance forces generated between a soft-magnetic stator and an impeller comprising a permanent magnet. Active levitation, on the other hand, is realized with feedback control. Gruber et al. (2015) developed a bearingless slice motor that drives a reluctance rotor. In such an embodiment, the magnet is eliminated from the rotor and placed on the stator to create a homopolar bias flux for passive stabilization of the rotor in axial and tilting directions.